This invention relates to a novel pressure relief valve construction and specifically for a pressure relief valve for use in relieving gas pressure build-up in rotating equipment such as pumps, gear boxes, spindles, etc. In the prior art, most pressure relief valves have used spring pressure or fluid pressure to control the operation of the relief valve. This is to ensure that the relief valve will operate to relieve the pressure at a predetermined pressure and to prevent damage to the rotating equipment.
In addition, in the prior art, check valves which prevent flow in one direction and allow flow in the opposite direction have been in existence for many years. There are many types of check valves including pivoting flappers which have poor low pressure drop characteristics. There have also been check valves employing ball-type closure members where the ball is always in the path of the flow. Such ball check members are not useful without major modifications to insure the maximum flow in both directions. In almost all of the prior art, ball-type check valves utilize a predetermined spring pressure of substantial value on the closing side to insure closure.